1. Field of the Invention
The present invention relates to a display device for enhancing the image quality of a display panel and a display method thereof, and more particularly, to a display device for enhancing the image quality of a display panel using a RGBW (red, green, blue, and white) color filter, and a display method thereof.
2. Description of Related Art
FIG. 1 is a circuit block diagram of a conventional liquid crystal display (LCD). The gate drive integrated circuits (GD1-GDn) of a gate driver 101 are used to turn on and turn off the thin film transistor of an LCD panel 103, and the source drive integrated circuits (SD1-SDm) of a source driver 102 are used to output data to a liquid crystal capacitor to make the voltage thereof reach a desired level at the time that the thin film transistor is turned on. In other words, only one pixel datum is written by each source line during each horizontal period. FIG. 2 is a circuit diagram of the conventional LCD panel 103. For example, as for one pixel in FIG. 2, when the transistor T1 is turned on by the gate line G0, the data is input to the liquid crystal capacitor C1 by the source line Sn.
FIG. 3 is a positional distribution diagram of some pixels of the conventional LCD panel 103. For illustration purpose, R, G, and B represent red, green, and blue, respectively. For example, (1,1), (2,1), (3,1), (4,1), (1,4), (2,4), (3,4), and (4,4) represent red pixels. These pixels are written in according to the following sequence. First, the gate line G0 is turned on and then data is written into (1,1)-(1,6) . Then, the gate line G1 is turned on and then data is written into (2,1)-(2,6). The gate lines G2 and G3 have the same functions as the gate lines G1 and G2 and will not be described hereinafter.
FIG. 4A is a color distribution diagram of the RGB color filter in FIG. 3, where the colors R, G, and B are distributed in a strip shape. FIG. 4B is a color distribution diagram of the RGBW color filter. In the mosaic distribution diagram of the RGBW color filter in FIG. 4B, W represents white. Because the blocks W are newly added to this arrangement, the overall luminance of the panel is increased. According to the current driving techniques, in order to prevent the polarization of liquid crystals, the driving polarity of the LCD can be a frame inversion polarity, a column inversion polarity, a row inversion polarity, or a dot inversion polarity and FIGS. 5A, 5B, 5C, and 5D are their polarity distribution diagrams, respectively. In addition, in order to solve the frame flickering problem when the operating system, e.g. MICROSOFT WINDOWS, is shut down, a distribution diagram of the driving polarities of two-dot inversion is shown in FIG. 5E. In FIGS. 5A-5E, the sign “+” denotes that the voltage of data written into a liquid crystal is greater than a common voltage Vcom and the voltage of the data is positive with respect to the common voltage Vcom, and a sign “−” denotes that the voltage of data written into a liquid crystal is smaller than the common voltage Vcom and the voltage of the data is negative with respect to the common voltage Vcom. The polarity distribution in FIG. 5D is suitable for the RGB color filter in FIG. 4A to achieve the effect of dot inversion, but such polarity distribution causes a negative effect on the RGBW color filter in FIG. 4B.
When the above-mentioned RGBW color filter has the conventional driving polarities of a current LCD, as shown in FIG. 5A through 5D, the panel displays a monochrome in the frame inversion, thereby causing the flicker of frames and as shown in FIG. 5E, the row inversion occurs to cause horizontal crosstalk. Accordingly, both the frame inversion and the row inversion have negative effects on the image quality. FIG. 6A is a polarity distribution diagram when the dot inversion driving is adopted by the RGBW color filter. However, when a monochrome is displayed, the pixels of the whole frame have the same polarity. FIG. 6B is a polarity distribution diagram when the two-dot inversion driving is adopted by the RGBW color filter. However, when a monochrome is displayed, the row inversion occurs, thereby causing horizontal crosstalk. Therefore, a conventional pixel level simplex LCD panel using a RGBW color filter causes many disadvantages.
U.S. Pat. No. 6,833,888 discloses an LCD device having RGBW color filters. However, the RGBW color filters are arranged in a horizontal strip shape, which incurs poor space utilization. U.S. Pat. No. 6,954,191 discloses a RGBW-typed LCD device. However, a complicated drive circuit should be redesigned for the LCD.